Implemented module dependency sort, that returns modules in order in which they shoul...
[controller.git] / opendaylight / sal / yang-prototype / code-generator / yang-model-parser-impl / src / main / java / org / opendaylight / controller / yang / model / parser / impl / YangModelParserImpl.java
index 27a65c1168f24fa822f1c13175d4c4a5a0cef0e2..35c04a8713bcae29908491b443b726a5a83aabe6 100644 (file)
@@ -12,13 +12,16 @@ import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.InputStream;
+import java.net.URI;
 import java.util.ArrayList;
-import java.util.Calendar;
+import java.util.Collections;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.NoSuchElementException;
 import java.util.Set;
 import java.util.TreeMap;
 
@@ -29,11 +32,11 @@ import org.antlr.v4.runtime.tree.ParseTreeWalker;
 import org.opendaylight.controller.antlrv4.code.gen.YangLexer;
 import org.opendaylight.controller.antlrv4.code.gen.YangParser;
 import org.opendaylight.controller.yang.common.QName;
-import org.opendaylight.controller.yang.model.api.AugmentationSchema;
 import org.opendaylight.controller.yang.model.api.DataSchemaNode;
 import org.opendaylight.controller.yang.model.api.ExtensionDefinition;
 import org.opendaylight.controller.yang.model.api.Module;
 import org.opendaylight.controller.yang.model.api.ModuleImport;
+import org.opendaylight.controller.yang.model.api.MustDefinition;
 import org.opendaylight.controller.yang.model.api.NotificationDefinition;
 import org.opendaylight.controller.yang.model.api.RpcDefinition;
 import org.opendaylight.controller.yang.model.api.SchemaContext;
@@ -49,18 +52,35 @@ import org.opendaylight.controller.yang.model.api.type.StringTypeDefinition;
 import org.opendaylight.controller.yang.model.parser.api.YangModelParser;
 import org.opendaylight.controller.yang.model.parser.builder.api.AugmentationSchemaBuilder;
 import org.opendaylight.controller.yang.model.parser.builder.api.AugmentationTargetBuilder;
+import org.opendaylight.controller.yang.model.parser.builder.api.Builder;
 import org.opendaylight.controller.yang.model.parser.builder.api.ChildNodeBuilder;
 import org.opendaylight.controller.yang.model.parser.builder.api.DataSchemaNodeBuilder;
+import org.opendaylight.controller.yang.model.parser.builder.api.GroupingBuilder;
 import org.opendaylight.controller.yang.model.parser.builder.api.TypeAwareBuilder;
 import org.opendaylight.controller.yang.model.parser.builder.api.TypeDefinitionBuilder;
+import org.opendaylight.controller.yang.model.parser.builder.api.UsesNodeBuilder;
+import org.opendaylight.controller.yang.model.parser.builder.impl.AnyXmlBuilder;
+import org.opendaylight.controller.yang.model.parser.builder.impl.ChoiceBuilder;
+import org.opendaylight.controller.yang.model.parser.builder.impl.ContainerSchemaNodeBuilder;
 import org.opendaylight.controller.yang.model.parser.builder.impl.IdentitySchemaNodeBuilder;
+import org.opendaylight.controller.yang.model.parser.builder.impl.IdentityrefTypeBuilder;
+import org.opendaylight.controller.yang.model.parser.builder.impl.LeafListSchemaNodeBuilder;
+import org.opendaylight.controller.yang.model.parser.builder.impl.LeafSchemaNodeBuilder;
+import org.opendaylight.controller.yang.model.parser.builder.impl.ListSchemaNodeBuilder;
 import org.opendaylight.controller.yang.model.parser.builder.impl.ModuleBuilder;
 import org.opendaylight.controller.yang.model.parser.builder.impl.TypedefBuilder;
 import org.opendaylight.controller.yang.model.parser.builder.impl.UnionTypeBuilder;
+import org.opendaylight.controller.yang.model.parser.builder.impl.UnknownSchemaNodeBuilder;
+import org.opendaylight.controller.yang.model.parser.util.ModuleDependencySort;
+import org.opendaylight.controller.yang.model.parser.util.ModuleDependencySort.ModuleSimple;
+import org.opendaylight.controller.yang.model.parser.util.ParserUtils;
+import org.opendaylight.controller.yang.model.parser.util.RefineHolder;
 import org.opendaylight.controller.yang.model.parser.util.TypeConstraints;
 import org.opendaylight.controller.yang.model.parser.util.YangParseException;
 import org.opendaylight.controller.yang.model.util.ExtendedType;
+import org.opendaylight.controller.yang.model.util.IdentityrefType;
 import org.opendaylight.controller.yang.model.util.UnknownType;
+import org.opendaylight.controller.yang.model.validator.YangModelBasicValidator;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -70,22 +90,28 @@ public class YangModelParserImpl implements YangModelParser {
             .getLogger(YangModelParserImpl.class);
 
     @Override
-    public Module parseYangModel(final String yangFile) {
-        final Map<String, TreeMap<Date, ModuleBuilder>> modules = resolveModuleBuildersFromStreams(yangFile);
-        final Set<Module> result = build(modules);
-        return result.iterator().next();
-    }
-
-    @Override
-    public Set<Module> parseYangModels(final String... yangFiles) {
-        final Map<String, TreeMap<Date, ModuleBuilder>> modules = resolveModuleBuildersFromStreams(yangFiles);
-        return build(modules);
+    public Set<Module> parseYangModels(final List<File> yangFiles) {
+        if (yangFiles != null) {
+            final List<InputStream> inputStreams = new ArrayList<InputStream>();
+
+            for (final File yangFile : yangFiles) {
+                try {
+                    inputStreams.add(new FileInputStream(yangFile));
+                } catch (FileNotFoundException e) {
+                    logger.warn("Exception while reading yang file: "
+                            + yangFile.getName(), e);
+                }
+            }
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules = resolveModuleBuilders(inputStreams);
+            return build(modules);
+        }
+        return Collections.emptySet();
     }
 
     @Override
     public Set<Module> parseYangModelsFromStreams(
-            final InputStream... yangModelStreams) {
-        final Map<String, TreeMap<Date, ModuleBuilder>> modules = resolveModuleBuildersFromStreams(yangModelStreams);
+            final List<InputStream> yangModelStreams) {
+        final Map<String, TreeMap<Date, ModuleBuilder>> modules = resolveModuleBuilders(yangModelStreams);
         return build(modules);
     }
 
@@ -94,31 +120,16 @@ public class YangModelParserImpl implements YangModelParser {
         return new SchemaContextImpl(modules);
     }
 
-    private Map<String, TreeMap<Date, ModuleBuilder>> resolveModuleBuildersFromStreams(
-            String... yangFiles) {
-        InputStream[] streams = new InputStream[yangFiles.length];
-        FileInputStream inStream = null;
-        for (int i = 0; i < yangFiles.length; i++) {
-            final String yangFileName = yangFiles[i];
-            final File yangFile = new File(yangFileName);
-            try {
-                inStream = new FileInputStream(yangFile);
-            } catch (FileNotFoundException e) {
-                logger.warn("Exception while reading yang stream: " + inStream,
-                        e);
-            }
-            streams[i] = inStream;
-        }
-        return resolveModuleBuildersFromStreams(streams);
-    }
-
-    private Map<String, TreeMap<Date, ModuleBuilder>> resolveModuleBuildersFromStreams(
-            InputStream... yangFiles) {
+    private Map<String, TreeMap<Date, ModuleBuilder>> resolveModuleBuilders(
+            final List<InputStream> yangFileStreams) {
         final Map<String, TreeMap<Date, ModuleBuilder>> modules = new HashMap<String, TreeMap<Date, ModuleBuilder>>();
         final ParseTreeWalker walker = new ParseTreeWalker();
-        final List<ParseTree> trees = parseStreams(yangFiles);
+        final List<ParseTree> trees = parseStreams(yangFileStreams);
         final ModuleBuilder[] builders = new ModuleBuilder[trees.size()];
 
+        // validate yang
+        new YangModelBasicValidator(walker).validate(trees);
+
         YangModelParserListenerImpl yangModelParser = null;
         for (int i = 0; i < trees.size(); i++) {
             yangModelParser = new YangModelParserListenerImpl();
@@ -126,11 +137,14 @@ public class YangModelParserImpl implements YangModelParser {
             builders[i] = yangModelParser.getModuleBuilder();
         }
 
+        // module dependency graph sorted
+        List<ModuleSimple> sorted = new ModuleDependencySort(builders).sort();
+
         for (ModuleBuilder builder : builders) {
             final String builderName = builder.getName();
             Date builderRevision = builder.getRevision();
             if (builderRevision == null) {
-                builderRevision = createEpochTime();
+                builderRevision = new Date(0L);
             }
             TreeMap<Date, ModuleBuilder> builderByRevision = modules
                     .get(builderName);
@@ -143,7 +157,7 @@ public class YangModelParserImpl implements YangModelParser {
         return modules;
     }
 
-    private List<ParseTree> parseStreams(InputStream... yangStreams) {
+    private List<ParseTree> parseStreams(final List<InputStream> yangStreams) {
         final List<ParseTree> trees = new ArrayList<ParseTree>();
         for (InputStream yangStream : yangStreams) {
             trees.add(parseStream(yangStream));
@@ -151,7 +165,7 @@ public class YangModelParserImpl implements YangModelParser {
         return trees;
     }
 
-    private ParseTree parseStream(InputStream yangStream) {
+    private ParseTree parseStream(final InputStream yangStream) {
         ParseTree result = null;
         try {
             final ANTLRInputStream input = new ANTLRInputStream(yangStream);
@@ -165,16 +179,18 @@ public class YangModelParserImpl implements YangModelParser {
         return result;
     }
 
-    private Set<Module> build(Map<String, TreeMap<Date, ModuleBuilder>> modules) {
-        // validate
+    private Set<Module> build(
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules) {
+        // fix unresolved nodes
         for (Map.Entry<String, TreeMap<Date, ModuleBuilder>> entry : modules
                 .entrySet()) {
             for (Map.Entry<Date, ModuleBuilder> childEntry : entry.getValue()
                     .entrySet()) {
-                ModuleBuilder moduleBuilder = childEntry.getValue();
-                validateModule(modules, moduleBuilder);
+                final ModuleBuilder moduleBuilder = childEntry.getValue();
+                fixUnresolvedNodes(modules, moduleBuilder);
             }
         }
+        resolveAugments(modules);
 
         // build
         final Set<Module> result = new HashSet<Module>();
@@ -183,8 +199,8 @@ public class YangModelParserImpl implements YangModelParser {
             final Map<Date, Module> modulesByRevision = new HashMap<Date, Module>();
             for (Map.Entry<Date, ModuleBuilder> childEntry : entry.getValue()
                     .entrySet()) {
-                ModuleBuilder moduleBuilder = childEntry.getValue();
-                Module module = moduleBuilder.build();
+                final ModuleBuilder moduleBuilder = childEntry.getValue();
+                final Module module = moduleBuilder.build();
                 modulesByRevision.put(childEntry.getKey(), module);
                 result.add(module);
             }
@@ -192,12 +208,13 @@ public class YangModelParserImpl implements YangModelParser {
         return result;
     }
 
-    private void validateModule(
-            Map<String, TreeMap<Date, ModuleBuilder>> modules,
-            ModuleBuilder builder) {
+    private void fixUnresolvedNodes(
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder builder) {
         resolveDirtyNodes(modules, builder);
-        resolveAugments(modules, builder);
         resolveIdentities(modules, builder);
+        resolveUses(modules, builder);
+        resolveUnknownNodes(modules, builder);
     }
 
     /**
@@ -210,47 +227,53 @@ public class YangModelParserImpl implements YangModelParser {
      *            current module
      */
     private void resolveDirtyNodes(
-            Map<String, TreeMap<Date, ModuleBuilder>> modules,
-            ModuleBuilder module) {
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder module) {
         final Map<List<String>, TypeAwareBuilder> dirtyNodes = module
                 .getDirtyNodes();
         if (!dirtyNodes.isEmpty()) {
             for (Map.Entry<List<String>, TypeAwareBuilder> entry : dirtyNodes
                     .entrySet()) {
 
-                TypeAwareBuilder typeToResolve = entry.getValue();
-                if (typeToResolve instanceof UnionTypeBuilder) {
-                    UnionTypeBuilder union = (UnionTypeBuilder) typeToResolve;
-                    List<TypeDefinition<?>> unionTypes = union.getTypes();
-                    List<UnknownType> toRemove = new ArrayList<UnknownType>();
+                final TypeAwareBuilder nodeToResolve = entry.getValue();
+                // different handling for union types
+                if (nodeToResolve instanceof UnionTypeBuilder) {
+                    final UnionTypeBuilder union = (UnionTypeBuilder) nodeToResolve;
+                    final List<TypeDefinition<?>> unionTypes = union.getTypes();
+                    final List<UnknownType> toRemove = new ArrayList<UnknownType>();
                     for (TypeDefinition<?> td : unionTypes) {
                         if (td instanceof UnknownType) {
-                            UnknownType unknownType = (UnknownType) td;
-                            TypeDefinitionBuilder resolvedType = findTargetTypeUnion(
-                                    typeToResolve, unknownType, modules, module);
+                            final UnknownType unknownType = (UnknownType) td;
+                            final TypeDefinitionBuilder resolvedType = resolveTypeUnion(
+                                    nodeToResolve, unknownType, modules, module);
                             union.setType(resolvedType);
                             toRemove.add(unknownType);
                         }
                     }
                     unionTypes.removeAll(toRemove);
+                } else if (nodeToResolve.getTypedef() instanceof IdentityrefTypeBuilder) {
+                    IdentityrefTypeBuilder idref = (IdentityrefTypeBuilder) nodeToResolve
+                            .getTypedef();
+                    nodeToResolve.setType(new IdentityrefType(findFullQName(
+                            modules, module, idref), idref.getPath()));
                 } else {
-                    TypeDefinitionBuilder resolvedType = findTargetType(
-                            typeToResolve, modules, module);
-                    typeToResolve.setType(resolvedType);
+                    final TypeDefinitionBuilder resolvedType = resolveType(
+                            nodeToResolve, modules, module);
+                    nodeToResolve.setType(resolvedType);
                 }
             }
         }
     }
 
-    private TypeDefinitionBuilder findTargetType(
-            TypeAwareBuilder typeToResolve,
-            Map<String, TreeMap<Date, ModuleBuilder>> modules,
-            ModuleBuilder builder) {
-        TypeConstraints constraints = new TypeConstraints();
+    private TypeDefinitionBuilder resolveType(
+            final TypeAwareBuilder typeToResolve,
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder builder) {
+        final TypeConstraints constraints = new TypeConstraints();
 
-        TypeDefinitionBuilder targetType = findTypedef(typeToResolve, modules,
-                builder);
-        TypeConstraints tConstraints = findConstraints(typeToResolve,
+        final TypeDefinitionBuilder targetType = getTypedefBuilder(
+                typeToResolve, modules, builder);
+        final TypeConstraints tConstraints = findConstraints(typeToResolve,
                 constraints, modules, builder);
         targetType.setRanges(tConstraints.getRange());
         targetType.setLengths(tConstraints.getLength());
@@ -260,15 +283,16 @@ public class YangModelParserImpl implements YangModelParser {
         return targetType;
     }
 
-    private TypeDefinitionBuilder findTargetTypeUnion(
-            TypeAwareBuilder typeToResolve, UnknownType unknownType,
-            Map<String, TreeMap<Date, ModuleBuilder>> modules,
-            ModuleBuilder builder) {
-        TypeConstraints constraints = new TypeConstraints();
+    private TypeDefinitionBuilder resolveTypeUnion(
+            final TypeAwareBuilder typeToResolve,
+            final UnknownType unknownType,
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder builder) {
+        final TypeConstraints constraints = new TypeConstraints();
 
-        TypeDefinitionBuilder targetType = findTypedefUnion(typeToResolve,
+        final TypeDefinitionBuilder targetType = getUnionBuilder(typeToResolve,
                 unknownType, modules, builder);
-        TypeConstraints tConstraints = findConstraints(typeToResolve,
+        final TypeConstraints tConstraints = findConstraints(typeToResolve,
                 constraints, modules, builder);
         targetType.setRanges(tConstraints.getRange());
         targetType.setLengths(tConstraints.getLength());
@@ -278,68 +302,66 @@ public class YangModelParserImpl implements YangModelParser {
         return targetType;
     }
 
-    private TypeDefinitionBuilder findTypedef(TypeAwareBuilder typeToResolve,
-            Map<String, TreeMap<Date, ModuleBuilder>> modules,
-            ModuleBuilder builder) {
+    private TypeDefinitionBuilder getTypedefBuilder(
+            final TypeAwareBuilder nodeToResolve,
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder builder) {
 
-        TypeDefinition<?> baseTypeToResolve = typeToResolve.getType();
-        if (baseTypeToResolve != null
-                && !(baseTypeToResolve instanceof UnknownType)) {
-            return (TypeDefinitionBuilder) typeToResolve;
+        final TypeDefinition<?> nodeToResolveBase = nodeToResolve.getType();
+        if (nodeToResolveBase != null
+                && !(nodeToResolveBase instanceof UnknownType)) {
+            return (TypeDefinitionBuilder) nodeToResolve;
         }
 
-        UnknownType unknownType = (UnknownType) typeToResolve.getType();
-
-        QName unknownTypeQName = unknownType.getQName();
-        String unknownTypeName = unknownTypeQName.getLocalName();
-        String unknownTypePrefix = unknownTypeQName.getPrefix();
+        final UnknownType unknownType = (UnknownType) nodeToResolve.getType();
+        final QName unknownTypeQName = unknownType.getQName();
 
         // search for module which contains referenced typedef
-        ModuleBuilder dependentModule = findDependentModule(modules, builder,
-                unknownTypePrefix);
-        TypeDefinitionBuilder lookedUpBuilder = findTypedefBuilder(
-                dependentModule.getModuleTypedefs(), unknownTypeName);
-
-        TypeDefinitionBuilder lookedUpBuilderCopy = copyTypedefBuilder(
-                lookedUpBuilder, typeToResolve instanceof TypeDefinitionBuilder);
-        TypeDefinitionBuilder resolvedCopy = resolveCopiedBuilder(
+        final ModuleBuilder dependentModule = findDependentModule(modules,
+                builder, unknownTypeQName.getPrefix());
+        final TypeDefinitionBuilder lookedUpBuilder = findTypedefBuilderByName(
+                dependentModule, unknownTypeQName.getLocalName());
+
+        final TypeDefinitionBuilder lookedUpBuilderCopy = copyTypedefBuilder(
+                lookedUpBuilder, nodeToResolve instanceof TypeDefinitionBuilder);
+        final TypeDefinitionBuilder resolvedCopy = resolveCopiedBuilder(
                 lookedUpBuilderCopy, modules, dependentModule);
         return resolvedCopy;
     }
 
-    private TypeDefinitionBuilder findTypedefUnion(
-            TypeAwareBuilder typeToResolve, UnknownType unknownType,
-            Map<String, TreeMap<Date, ModuleBuilder>> modules,
-            ModuleBuilder builder) {
+    private TypeDefinitionBuilder getUnionBuilder(
+            final TypeAwareBuilder nodeToResolve,
+            final UnknownType unknownType,
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder module) {
 
-        TypeDefinition<?> baseTypeToResolve = typeToResolve.getType();
+        final TypeDefinition<?> baseTypeToResolve = nodeToResolve.getType();
         if (baseTypeToResolve != null
                 && !(baseTypeToResolve instanceof UnknownType)) {
-            return (TypeDefinitionBuilder) typeToResolve;
+            return (TypeDefinitionBuilder) nodeToResolve;
         }
 
-        QName unknownTypeQName = unknownType.getQName();
-        String unknownTypeName = unknownTypeQName.getLocalName();
-        String unknownTypePrefix = unknownTypeQName.getPrefix();
-
+        final QName unknownTypeQName = unknownType.getQName();
         // search for module which contains referenced typedef
-        ModuleBuilder dependentModule = findDependentModule(modules, builder,
-                unknownTypePrefix);
-        TypeDefinitionBuilder lookedUpBuilder = findTypedefBuilder(
-                dependentModule.getModuleTypedefs(), unknownTypeName);
-
-        TypeDefinitionBuilder lookedUpBuilderCopy = copyTypedefBuilder(
-                lookedUpBuilder, typeToResolve instanceof TypeDefinitionBuilder);
-        TypeDefinitionBuilder resolvedCopy = resolveCopiedBuilder(
+        final ModuleBuilder dependentModule = findDependentModule(modules,
+                module, unknownTypeQName.getPrefix());
+        final TypeDefinitionBuilder lookedUpBuilder = findTypedefBuilderByName(
+                dependentModule, unknownTypeQName.getLocalName());
+
+        final TypeDefinitionBuilder lookedUpBuilderCopy = copyTypedefBuilder(
+                lookedUpBuilder, nodeToResolve instanceof TypeDefinitionBuilder);
+        final TypeDefinitionBuilder resolvedCopy = resolveCopiedBuilder(
                 lookedUpBuilderCopy, modules, dependentModule);
         return resolvedCopy;
     }
 
-    private TypeDefinitionBuilder copyTypedefBuilder(TypeDefinitionBuilder old,
-            boolean seekByTypedefBuilder) {
+    private TypeDefinitionBuilder copyTypedefBuilder(
+            final TypeDefinitionBuilder old, final boolean seekByTypedefBuilder) {
         if (old instanceof UnionTypeBuilder) {
-            UnionTypeBuilder oldUnion = (UnionTypeBuilder) old;
-            UnionTypeBuilder newUnion = new UnionTypeBuilder();
+            final UnionTypeBuilder oldUnion = (UnionTypeBuilder) old;
+            final UnionTypeBuilder newUnion = new UnionTypeBuilder(
+                    oldUnion.getActualPath(), oldUnion.getNamespace(),
+                    oldUnion.getRevision());
             for (TypeDefinition<?> td : oldUnion.getTypes()) {
                 newUnion.setType(td);
             }
@@ -349,17 +371,19 @@ public class YangModelParserImpl implements YangModelParser {
             return newUnion;
         }
 
-        QName oldQName = old.getQName();
-        QName newQName = new QName(oldQName.getNamespace(),
-                oldQName.getRevision(), oldQName.getPrefix(),
-                oldQName.getLocalName());
-        TypeDefinitionBuilder tdb = new TypedefBuilder(newQName);
+        final QName oldName = old.getQName();
+        final QName newName = new QName(oldName.getNamespace(),
+                oldName.getRevision(), oldName.getPrefix(),
+                oldName.getLocalName());
+        final TypeDefinitionBuilder tdb = new TypedefBuilder(newName);
 
         tdb.setRanges(old.getRanges());
         tdb.setLengths(old.getLengths());
         tdb.setPatterns(old.getPatterns());
+        tdb.setFractionDigits(old.getFractionDigits());
+        tdb.setPath(old.getPath());
 
-        TypeDefinition<?> oldType = old.getType();
+        final TypeDefinition<?> oldType = old.getType();
         if (oldType == null) {
             tdb.setType(old.getTypedef());
         } else {
@@ -377,18 +401,18 @@ public class YangModelParserImpl implements YangModelParser {
     }
 
     private TypeDefinitionBuilder resolveCopiedBuilder(
-            TypeDefinitionBuilder copied,
-            Map<String, TreeMap<Date, ModuleBuilder>> modules,
-            ModuleBuilder builder) {
-
-        if (copied instanceof UnionTypeBuilder) {
-            UnionTypeBuilder union = (UnionTypeBuilder) copied;
-            List<TypeDefinition<?>> unionTypes = union.getTypes();
-            List<UnknownType> toRemove = new ArrayList<UnknownType>();
+            final TypeDefinitionBuilder copy,
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder builder) {
+
+        if (copy instanceof UnionTypeBuilder) {
+            final UnionTypeBuilder union = (UnionTypeBuilder) copy;
+            final List<TypeDefinition<?>> unionTypes = union.getTypes();
+            final List<UnknownType> toRemove = new ArrayList<UnknownType>();
             for (TypeDefinition<?> td : unionTypes) {
                 if (td instanceof UnknownType) {
-                    UnknownType unknownType = (UnknownType) td;
-                    TypeDefinitionBuilder resolvedType = findTargetTypeUnion(
+                    final UnknownType unknownType = (UnknownType) td;
+                    final TypeDefinitionBuilder resolvedType = resolveTypeUnion(
                             union, unknownType, modules, builder);
                     union.setType(resolvedType);
                     toRemove.add(unknownType);
@@ -399,118 +423,113 @@ public class YangModelParserImpl implements YangModelParser {
             return union;
         }
 
-        TypeDefinition<?> base = copied.getType();
-        TypeDefinitionBuilder baseTdb = copied.getTypedef();
+        final TypeDefinition<?> base = copy.getType();
+        final TypeDefinitionBuilder baseTdb = copy.getTypedef();
         if (base != null && !(base instanceof UnknownType)) {
-            return copied;
+            return copy;
         } else if (base instanceof UnknownType) {
-            UnknownType unknownType = (UnknownType) base;
-            QName unknownTypeQName = unknownType.getQName();
-            String unknownTypePrefix = unknownTypeQName.getPrefix();
-            ModuleBuilder dependentModule = findDependentModule(modules,
+            final UnknownType unknownType = (UnknownType) base;
+            final QName unknownTypeQName = unknownType.getQName();
+            final String unknownTypePrefix = unknownTypeQName.getPrefix();
+            final ModuleBuilder dependentModule = findDependentModule(modules,
                     builder, unknownTypePrefix);
-            TypeDefinitionBuilder unknownTypeBuilder = findTypedef(copied,
+            final TypeDefinitionBuilder utBuilder = getTypedefBuilder(copy,
                     modules, dependentModule);
-            copied.setType(unknownTypeBuilder);
-            return copied;
+            copy.setType(utBuilder);
+            return copy;
         } else if (base == null && baseTdb != null) {
             // make a copy of baseTypeDef and call again
-            TypeDefinitionBuilder baseTdbCopy = copyTypedefBuilder(baseTdb,
-                    true);
-            TypeDefinitionBuilder baseTdbCopyResolved = resolveCopiedBuilder(
+            final TypeDefinitionBuilder baseTdbCopy = copyTypedefBuilder(
+                    baseTdb, true);
+            final TypeDefinitionBuilder baseTdbCopyResolved = resolveCopiedBuilder(
                     baseTdbCopy, modules, builder);
-            copied.setType(baseTdbCopyResolved);
-            return copied;
+            copy.setType(baseTdbCopyResolved);
+            return copy;
         } else {
-            throw new IllegalStateException(
-                    "TypeDefinitionBuilder in unexpected state");
+            throw new IllegalStateException("Failed to resolve type "
+                    + copy.getQName().getLocalName());
         }
     }
 
-    private TypeDefinitionBuilder findTypedef(QName unknownTypeQName,
-            Map<String, TreeMap<Date, ModuleBuilder>> modules,
-            ModuleBuilder builder) {
-
-        String unknownTypeName = unknownTypeQName.getLocalName();
-        String unknownTypePrefix = unknownTypeQName.getPrefix();
-
+    private TypeDefinitionBuilder findTypedefBuilder(
+            final QName unknownTypeQName,
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder builder) {
         // search for module which contains referenced typedef
-        ModuleBuilder dependentModule = findDependentModule(modules, builder,
-                unknownTypePrefix);
-
-        TypeDefinitionBuilder lookedUpBuilder = findTypedefBuilder(
-                dependentModule.getModuleTypedefs(), unknownTypeName);
-
-        TypeDefinitionBuilder copied = copyTypedefBuilder(lookedUpBuilder, true);
-        return copied;
+        final ModuleBuilder dependentModule = findDependentModule(modules,
+                builder, unknownTypeQName.getPrefix());
+        final TypeDefinitionBuilder lookedUpBuilder = findTypedefBuilderByName(
+                dependentModule, unknownTypeQName.getLocalName());
+        return copyTypedefBuilder(lookedUpBuilder, true);
     }
 
-    private TypeConstraints findConstraints(TypeAwareBuilder typeToResolve,
-            TypeConstraints constraints,
-            Map<String, TreeMap<Date, ModuleBuilder>> modules,
-            ModuleBuilder builder) {
-
+    private TypeConstraints findConstraints(
+            final TypeAwareBuilder nodeToResolve,
+            final TypeConstraints constraints,
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder builder) {
         // union type cannot be restricted
-        if (typeToResolve instanceof UnionTypeBuilder) {
+        if (nodeToResolve instanceof UnionTypeBuilder) {
             return constraints;
         }
 
         // if referenced type is UnknownType again, search recursively with
         // current constraints
-        TypeDefinition<?> referencedType = typeToResolve.getType();
+        final TypeDefinition<?> referencedType = nodeToResolve.getType();
+        List<RangeConstraint> ranges = Collections.emptyList();
+        List<LengthConstraint> lengths = Collections.emptyList();
+        List<PatternConstraint> patterns = Collections.emptyList();
+        Integer fractionDigits = null;
         if (referencedType == null) {
-            TypeDefinitionBuilder tdb = (TypeDefinitionBuilder) typeToResolve;
-            final List<RangeConstraint> ranges = tdb.getRanges();
+            final TypeDefinitionBuilder tdb = (TypeDefinitionBuilder) nodeToResolve;
+            ranges = tdb.getRanges();
             constraints.addRanges(ranges);
-            final List<LengthConstraint> lengths = tdb.getLengths();
+            lengths = tdb.getLengths();
             constraints.addLengths(lengths);
-            final List<PatternConstraint> patterns = tdb.getPatterns();
+            patterns = tdb.getPatterns();
             constraints.addPatterns(patterns);
-            final Integer fractionDigits = tdb.getFractionDigits();
+            fractionDigits = tdb.getFractionDigits();
             constraints.setFractionDigits(fractionDigits);
             return constraints;
         } else if (referencedType instanceof ExtendedType) {
-            ExtendedType ext = (ExtendedType) referencedType;
-            final List<RangeConstraint> ranges = ext.getRanges();
+            final ExtendedType ext = (ExtendedType) referencedType;
+            ranges = ext.getRanges();
             constraints.addRanges(ranges);
-            final List<LengthConstraint> lengths = ext.getLengths();
+            lengths = ext.getLengths();
             constraints.addLengths(lengths);
-            final List<PatternConstraint> patterns = ext.getPatterns();
+            patterns = ext.getPatterns();
             constraints.addPatterns(patterns);
-            final Integer fractionDigits = ext.getFractionDigits();
+            fractionDigits = ext.getFractionDigits();
             constraints.setFractionDigits(fractionDigits);
             return findConstraints(
-                    findTypedef(ext.getQName(), modules, builder), constraints,
-                    modules, builder);
+                    findTypedefBuilder(ext.getQName(), modules, builder),
+                    constraints, modules, builder);
         } else if (referencedType instanceof UnknownType) {
-            UnknownType unknown = (UnknownType) referencedType;
-
-            final List<RangeConstraint> ranges = unknown.getRangeStatements();
+            final UnknownType unknown = (UnknownType) referencedType;
+            ranges = unknown.getRangeStatements();
             constraints.addRanges(ranges);
-            final List<LengthConstraint> lengths = unknown
-                    .getLengthStatements();
+            lengths = unknown.getLengthStatements();
             constraints.addLengths(lengths);
-            final List<PatternConstraint> patterns = unknown.getPatterns();
+            patterns = unknown.getPatterns();
             constraints.addPatterns(patterns);
-            final Integer fractionDigits = unknown.getFractionDigits();
+            fractionDigits = unknown.getFractionDigits();
             constraints.setFractionDigits(fractionDigits);
 
             String unknownTypePrefix = unknown.getQName().getPrefix();
             if (unknownTypePrefix == null || "".equals(unknownTypePrefix)) {
                 unknownTypePrefix = builder.getPrefix();
             }
-            ModuleBuilder dependentModule = findDependentModule(modules,
+            final ModuleBuilder dependentModule = findDependentModule(modules,
                     builder, unknown.getQName().getPrefix());
-            TypeDefinitionBuilder unknownTypeBuilder = findTypedef(
+            final TypeDefinitionBuilder utBuilder = findTypedefBuilder(
                     unknown.getQName(), modules, builder);
-            return findConstraints(unknownTypeBuilder, constraints, modules,
+            return findConstraints(utBuilder, constraints, modules,
                     dependentModule);
         } else {
             // HANDLE BASE YANG TYPE
             mergeConstraints(referencedType, constraints);
             return constraints;
         }
-
     }
 
     /**
@@ -523,9 +542,11 @@ public class YangModelParserImpl implements YangModelParser {
      *            name of searched typedef
      * @return typedef with name equals to given name
      */
-    private TypeDefinitionBuilder findTypedefBuilder(
-            Set<TypeDefinitionBuilder> typedefs, String name) {
+    private TypeDefinitionBuilder findTypedefBuilderByName(
+            final ModuleBuilder dependentModule, final String name) {
         TypeDefinitionBuilder result = null;
+        final Set<TypeDefinitionBuilder> typedefs = dependentModule
+                .getModuleTypedefs();
         for (TypeDefinitionBuilder td : typedefs) {
             if (td.getQName().getLocalName().equals(name)) {
                 result = td;
@@ -533,8 +554,9 @@ public class YangModelParserImpl implements YangModelParser {
             }
         }
         if (result == null) {
-            throw new YangParseException(
-                    "Target module does not contain typedef '" + name + "'.");
+            throw new YangParseException("Target module '"
+                    + dependentModule.getName()
+                    + "' does not contain typedef '" + name + "'.");
         }
         return result;
     }
@@ -545,8 +567,8 @@ public class YangModelParserImpl implements YangModelParser {
      * @param referencedType
      * @param constraints
      */
-    private void mergeConstraints(TypeDefinition<?> referencedType,
-            TypeConstraints constraints) {
+    private void mergeConstraints(final TypeDefinition<?> referencedType,
+            final TypeConstraints constraints) {
 
         if (referencedType instanceof DecimalTypeDefinition) {
             constraints.addRanges(((DecimalTypeDefinition) referencedType)
@@ -569,55 +591,117 @@ public class YangModelParserImpl implements YangModelParser {
     }
 
     /**
-     * Go through all augmentation definitions and resolve them. This means find
-     * referenced node and add child nodes to it.
+     * Go through all augmentation definitions and resolve them. This method
+     * also finds referenced node and add child nodes to it.
      *
      * @param modules
      *            all available modules
-     * @param module
-     *            current module
      */
     private void resolveAugments(
-            Map<String, TreeMap<Date, ModuleBuilder>> modules,
-            ModuleBuilder module) {
-        Set<AugmentationSchemaBuilder> augmentBuilders = module
-                .getAddedAugments();
-
-        Set<AugmentationSchema> augments = new HashSet<AugmentationSchema>();
-        for (AugmentationSchemaBuilder augmentBuilder : augmentBuilders) {
-            SchemaPath augmentTargetSchemaPath = augmentBuilder.getTargetPath();
-            String prefix = null;
-            List<String> augmentTargetPath = new ArrayList<String>();
-
-            for (QName pathPart : augmentTargetSchemaPath.getPath()) {
-                prefix = pathPart.getPrefix();
-                augmentTargetPath.add(pathPart.getLocalName());
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules) {
+        final List<ModuleBuilder> allModulesList = new ArrayList<ModuleBuilder>();
+        final Set<ModuleBuilder> allModulesSet = new HashSet<ModuleBuilder>();
+        for (Map.Entry<String, TreeMap<Date, ModuleBuilder>> entry : modules
+                .entrySet()) {
+            for (Map.Entry<Date, ModuleBuilder> inner : entry.getValue()
+                    .entrySet()) {
+                allModulesList.add(inner.getValue());
+                allModulesSet.add(inner.getValue());
             }
-            ModuleBuilder dependentModule = findDependentModule(modules,
-                    module, prefix);
-            augmentTargetPath.add(0, dependentModule.getName());
+        }
 
-            AugmentationTargetBuilder augmentTarget = (AugmentationTargetBuilder) dependentModule
-                    .getNode(augmentTargetPath);
-            AugmentationSchema result = augmentBuilder.build();
-            augmentTarget.addAugmentation(result);
-            fillAugmentTarget(augmentBuilder, (ChildNodeBuilder) augmentTarget);
-            augments.add(result);
+        for (int i = 0; i < allModulesList.size(); i++) {
+            final ModuleBuilder module = allModulesList.get(i);
+            // try to resolve augments in module
+            resolveAugment(modules, module);
+            // while all augments are not resolved
+            final Iterator<ModuleBuilder> allModulesIterator = allModulesSet
+                    .iterator();
+            while (!(module.getAugmentsResolved() == module.getAddedAugments()
+                    .size())) {
+                ModuleBuilder nextModule = null;
+                // try resolve other module augments
+                try {
+                    nextModule = allModulesIterator.next();
+                    resolveAugment(modules, nextModule);
+                } catch (NoSuchElementException e) {
+                    throw new YangParseException(
+                            "Failed to resolve augments in module '"
+                                    + module.getName() + "'.", e);
+                }
+                // then try to resolve first module again
+                resolveAugment(modules, module);
+            }
         }
-        module.setAugmentations(augments);
     }
 
     /**
-     * Add all augment's child nodes to given target.
      *
-     * @param augment
-     * @param target
+     * @param modules
+     *            all available modules
+     * @param module
+     *            current module
      */
-    private void fillAugmentTarget(AugmentationSchemaBuilder augment,
-            ChildNodeBuilder target) {
-        for (DataSchemaNodeBuilder builder : augment.getChildNodes()) {
-            builder.setAugmenting(true);
-            target.addChildNode(builder);
+    private void resolveAugment(
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder module) {
+        if (module.getAugmentsResolved() < module.getAddedAugments().size()) {
+            for (AugmentationSchemaBuilder augmentBuilder : module
+                    .getAddedAugments()) {
+                final SchemaPath augmentTargetSchemaPath = augmentBuilder
+                        .getTargetPath();
+                final List<QName> path = augmentTargetSchemaPath.getPath();
+
+                int i = 0;
+                final QName qname = path.get(i);
+                String prefix = qname.getPrefix();
+                if (prefix == null) {
+                    prefix = module.getPrefix();
+                }
+
+                DataSchemaNodeBuilder currentParent = null;
+                final ModuleBuilder dependentModule = findDependentModule(
+                        modules, module, prefix);
+                for (DataSchemaNodeBuilder child : dependentModule
+                        .getChildNodes()) {
+                    final QName childQName = child.getQName();
+                    if (childQName.getLocalName().equals(qname.getLocalName())) {
+                        currentParent = child;
+                        i++;
+                        break;
+                    }
+                }
+
+                for (; i < path.size(); i++) {
+                    final QName currentQName = path.get(i);
+                    DataSchemaNodeBuilder newParent = null;
+                    for (DataSchemaNodeBuilder child : ((ChildNodeBuilder) currentParent)
+                            .getChildNodes()) {
+                        final QName childQName = child.getQName();
+                        if (childQName.getLocalName().equals(
+                                currentQName.getLocalName())) {
+                            newParent = child;
+                            break;
+                        }
+                    }
+                    if (newParent == null) {
+                        break; // node not found, quit search
+                    } else {
+                        currentParent = newParent;
+                    }
+                }
+
+                final QName currentQName = currentParent.getQName();
+                final QName lastAugmentPathElement = path.get(path.size() - 1);
+                if (currentQName.getLocalName().equals(
+                        lastAugmentPathElement.getLocalName())) {
+                    ParserUtils.fillAugmentTarget(augmentBuilder,
+                            (ChildNodeBuilder) currentParent);
+                    ((AugmentationTargetBuilder) currentParent)
+                            .addAugmentation(augmentBuilder);
+                    module.augmentResolved();
+                }
+            }
         }
     }
 
@@ -631,26 +715,27 @@ public class YangModelParserImpl implements YangModelParser {
      *            module being resolved
      */
     private void resolveIdentities(
-            Map<String, TreeMap<Date, ModuleBuilder>> modules,
-            ModuleBuilder module) {
-        Set<IdentitySchemaNodeBuilder> identities = module.getAddedIdentities();
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder module) {
+        final Set<IdentitySchemaNodeBuilder> identities = module
+                .getAddedIdentities();
         for (IdentitySchemaNodeBuilder identity : identities) {
-            String baseIdentityName = identity.getBaseIdentityName();
+            final String baseIdentityName = identity.getBaseIdentityName();
             if (baseIdentityName != null) {
                 String baseIdentityPrefix = null;
                 String baseIdentityLocalName = null;
                 if (baseIdentityName.contains(":")) {
-                    String[] splitted = baseIdentityName.split(":");
+                    final String[] splitted = baseIdentityName.split(":");
                     baseIdentityPrefix = splitted[0];
                     baseIdentityLocalName = splitted[1];
                 } else {
                     baseIdentityPrefix = module.getPrefix();
                     baseIdentityLocalName = baseIdentityName;
                 }
-                ModuleBuilder dependentModule = findDependentModule(modules,
-                        module, baseIdentityPrefix);
+                final ModuleBuilder dependentModule = findDependentModule(
+                        modules, module, baseIdentityPrefix);
 
-                Set<IdentitySchemaNodeBuilder> dependentModuleIdentities = dependentModule
+                final Set<IdentitySchemaNodeBuilder> dependentModuleIdentities = dependentModule
                         .getAddedIdentities();
                 for (IdentitySchemaNodeBuilder idBuilder : dependentModuleIdentities) {
                     if (idBuilder.getQName().getLocalName()
@@ -662,6 +747,267 @@ public class YangModelParserImpl implements YangModelParser {
         }
     }
 
+    /**
+     * Go through uses statements defined in current module and resolve their
+     * refine statements.
+     *
+     * @param modules
+     *            all modules
+     * @param module
+     *            module being resolved
+     */
+    private void resolveUses(
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder module) {
+        final Map<List<String>, UsesNodeBuilder> moduleUses = module
+                .getAddedUsesNodes();
+        for (Map.Entry<List<String>, UsesNodeBuilder> entry : moduleUses
+                .entrySet()) {
+            final List<String> key = entry.getKey();
+            final UsesNodeBuilder usesNode = entry.getValue();
+
+            final String groupingName = key.get(key.size() - 1);
+
+            for (RefineHolder refine : usesNode.getRefines()) {
+                // refine statements
+                final String defaultStr = refine.getDefaultStr();
+                final Boolean mandatory = refine.isMandatory();
+                final MustDefinition must = refine.getMust();
+                final Boolean presence = refine.isPresence();
+                final Integer min = refine.getMinElements();
+                final Integer max = refine.getMaxElements();
+                final List<UnknownSchemaNodeBuilder> unknownNodes = refine
+                        .getUnknownNodes();
+
+                Builder refineTarget = getRefineTargetBuilder(groupingName,
+                        refine, modules, module);
+                if (refineTarget instanceof LeafSchemaNodeBuilder) {
+                    final LeafSchemaNodeBuilder leaf = (LeafSchemaNodeBuilder) refineTarget;
+                    if (defaultStr != null && !("".equals(defaultStr))) {
+                        leaf.setDefaultStr(defaultStr);
+                    }
+                    if (mandatory != null) {
+                        leaf.getConstraints().setMandatory(mandatory);
+                    }
+                    if (must != null) {
+                        leaf.getConstraints().addMustDefinition(must);
+                    }
+                    if (unknownNodes != null) {
+                        for (UnknownSchemaNodeBuilder unknown : unknownNodes) {
+                            leaf.addUnknownSchemaNode(unknown);
+                        }
+                    }
+                    usesNode.addRefineNode(leaf);
+                } else if (refineTarget instanceof ContainerSchemaNodeBuilder) {
+                    final ContainerSchemaNodeBuilder container = (ContainerSchemaNodeBuilder) refineTarget;
+                    if (presence != null) {
+                        container.setPresence(presence);
+                    }
+                    if (must != null) {
+                        container.getConstraints().addMustDefinition(must);
+                    }
+                    if (unknownNodes != null) {
+                        for (UnknownSchemaNodeBuilder unknown : unknownNodes) {
+                            container.addUnknownSchemaNode(unknown);
+                        }
+                    }
+                    usesNode.addRefineNode(container);
+                } else if (refineTarget instanceof ListSchemaNodeBuilder) {
+                    final ListSchemaNodeBuilder list = (ListSchemaNodeBuilder) refineTarget;
+                    if (must != null) {
+                        list.getConstraints().addMustDefinition(must);
+                    }
+                    if (min != null) {
+                        list.getConstraints().setMinElements(min);
+                    }
+                    if (max != null) {
+                        list.getConstraints().setMaxElements(max);
+                    }
+                    if (unknownNodes != null) {
+                        for (UnknownSchemaNodeBuilder unknown : unknownNodes) {
+                            list.addUnknownSchemaNode(unknown);
+                        }
+                    }
+                } else if (refineTarget instanceof LeafListSchemaNodeBuilder) {
+                    final LeafListSchemaNodeBuilder leafList = (LeafListSchemaNodeBuilder) getRefineTargetBuilder(
+                            groupingName, refine, modules, module);
+                    if (must != null) {
+                        leafList.getConstraints().addMustDefinition(must);
+                    }
+                    if (min != null) {
+                        leafList.getConstraints().setMinElements(min);
+                    }
+                    if (max != null) {
+                        leafList.getConstraints().setMaxElements(max);
+                    }
+                    if (unknownNodes != null) {
+                        for (UnknownSchemaNodeBuilder unknown : unknownNodes) {
+                            leafList.addUnknownSchemaNode(unknown);
+                        }
+                    }
+                } else if (refineTarget instanceof ChoiceBuilder) {
+                    final ChoiceBuilder choice = (ChoiceBuilder) refineTarget;
+                    if (defaultStr != null) {
+                        choice.setDefaultCase(defaultStr);
+                    }
+                    if (mandatory != null) {
+                        choice.getConstraints().setMandatory(mandatory);
+                    }
+                    if (unknownNodes != null) {
+                        for (UnknownSchemaNodeBuilder unknown : unknownNodes) {
+                            choice.addUnknownSchemaNode(unknown);
+                        }
+                    }
+                } else if (refineTarget instanceof AnyXmlBuilder) {
+                    final AnyXmlBuilder anyXml = (AnyXmlBuilder) refineTarget;
+                    if (mandatory != null) {
+                        anyXml.getConstraints().setMandatory(mandatory);
+                    }
+                    if (must != null) {
+                        anyXml.getConstraints().addMustDefinition(must);
+                    }
+                    if (unknownNodes != null) {
+                        for (UnknownSchemaNodeBuilder unknown : unknownNodes) {
+                            anyXml.addUnknownSchemaNode(unknown);
+                        }
+                    }
+                }
+            }
+        }
+    }
+
+    /**
+     * Find original builder of refine node and return copy of this builder.
+     *
+     * @param groupingPath
+     *            path to grouping which contains node to refine
+     * @param refine
+     *            refine object containing informations about refine
+     * @param modules
+     *            all loaded modules
+     * @param module
+     *            current module
+     * @return copy of Builder object of node to be refined if it is present in
+     *         grouping, null otherwise
+     */
+    private Builder getRefineTargetBuilder(final String groupingPath,
+            final RefineHolder refine,
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder module) {
+        Builder result = null;
+        final Builder lookedUpBuilder = findRefineTargetBuilder(groupingPath,
+                refine.getName(), modules, module);
+        if (lookedUpBuilder instanceof LeafSchemaNodeBuilder) {
+            result = ParserUtils
+                    .copyLeafBuilder((LeafSchemaNodeBuilder) lookedUpBuilder);
+        } else if (lookedUpBuilder instanceof ContainerSchemaNodeBuilder) {
+            result = ParserUtils
+                    .copyContainerBuilder((ContainerSchemaNodeBuilder) lookedUpBuilder);
+        } else if (lookedUpBuilder instanceof ListSchemaNodeBuilder) {
+            result = ParserUtils
+                    .copyListBuilder((ListSchemaNodeBuilder) lookedUpBuilder);
+        } else if (lookedUpBuilder instanceof LeafListSchemaNodeBuilder) {
+            result = ParserUtils
+                    .copyLeafListBuilder((LeafListSchemaNodeBuilder) lookedUpBuilder);
+        } else if (lookedUpBuilder instanceof ChoiceBuilder) {
+            result = ParserUtils
+                    .copyChoiceBuilder((ChoiceBuilder) lookedUpBuilder);
+        } else if (lookedUpBuilder instanceof AnyXmlBuilder) {
+            result = ParserUtils
+                    .copyAnyXmlBuilder((AnyXmlBuilder) lookedUpBuilder);
+        } else {
+            throw new YangParseException("Target '" + refine.getName()
+                    + "' can not be refined");
+        }
+        return result;
+    }
+
+    /**
+     * Find builder of refine node.
+     *
+     * @param groupingPath
+     *            path to grouping which contains node to refine
+     * @param refineNodeName
+     *            name of node to be refined
+     * @param modules
+     *            all loaded modules
+     * @param module
+     *            current module
+     * @return Builder object of refine node if it is present in grouping, null
+     *         otherwise
+     */
+    private Builder findRefineTargetBuilder(final String groupingPath,
+            final String refineNodeName,
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder module) {
+        final SchemaPath path = ParserUtils.parseUsesPath(groupingPath);
+        final List<String> builderPath = new ArrayList<String>();
+        String prefix = null;
+        for (QName qname : path.getPath()) {
+            builderPath.add(qname.getLocalName());
+            prefix = qname.getPrefix();
+        }
+        if (prefix == null) {
+            prefix = module.getPrefix();
+        }
+
+        final ModuleBuilder dependentModule = findDependentModule(modules,
+                module, prefix);
+        builderPath.add(0, "grouping");
+        builderPath.add(0, dependentModule.getName());
+        final GroupingBuilder builder = (GroupingBuilder) dependentModule
+                .getNode(builderPath);
+
+        return builder.getChildNode(refineNodeName);
+    }
+
+    private QName findFullQName(
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder module, final IdentityrefTypeBuilder idref) {
+        QName result = null;
+        String baseString = idref.getBaseString();
+        if (baseString.contains(":")) {
+            String[] splittedBase = baseString.split(":");
+            if (splittedBase.length > 2) {
+                throw new YangParseException(
+                        "Failed to parse identityref base: " + baseString);
+            }
+            String prefix = splittedBase[0];
+            String name = splittedBase[1];
+            ModuleBuilder dependentModule = findDependentModule(modules,
+                    module, prefix);
+            result = new QName(dependentModule.getNamespace(),
+                    dependentModule.getRevision(), prefix, name);
+        } else {
+            result = new QName(module.getNamespace(), module.getRevision(),
+                    module.getPrefix(), baseString);
+        }
+        return result;
+    }
+
+    private void resolveUnknownNodes(
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder module) {
+        for (UnknownSchemaNodeBuilder usnb : module.getAddedUnknownNodes()) {
+            QName nodeType = usnb.getNodeType();
+            if (nodeType.getNamespace() == null
+                    || nodeType.getRevision() == null) {
+                try {
+                    ModuleBuilder dependentModule = findDependentModule(
+                            modules, module, nodeType.getPrefix());
+                    QName newNodeType = new QName(
+                            dependentModule.getNamespace(),
+                            dependentModule.getRevision(),
+                            nodeType.getPrefix(), nodeType.getLocalName());
+                    usnb.setNodeType(newNodeType);
+                } catch (YangParseException e) {
+                    logger.debug("Failed to find unknown node type: "
+                            + nodeType);
+                }
+            }
+        }
+    }
+
     /**
      * Find dependent module based on given prefix
      *
@@ -674,24 +1020,32 @@ public class YangModelParserImpl implements YangModelParser {
      * @return
      */
     private ModuleBuilder findDependentModule(
-            Map<String, TreeMap<Date, ModuleBuilder>> modules,
-            ModuleBuilder module, String prefix) {
+            final Map<String, TreeMap<Date, ModuleBuilder>> modules,
+            final ModuleBuilder module, final String prefix) {
         ModuleBuilder dependentModule = null;
         Date dependentModuleRevision = null;
 
         if (prefix.equals(module.getPrefix())) {
             dependentModule = module;
         } else {
-            ModuleImport dependentModuleImport = getModuleImport(module, prefix);
+            final ModuleImport dependentModuleImport = ParserUtils
+                    .getModuleImport(module, prefix);
             if (dependentModuleImport == null) {
                 throw new YangParseException("No import found with prefix '"
                         + prefix + "' in module " + module.getName() + "'.");
             }
-            String dependentModuleName = dependentModuleImport.getModuleName();
+            final String dependentModuleName = dependentModuleImport
+                    .getModuleName();
             dependentModuleRevision = dependentModuleImport.getRevision();
 
-            TreeMap<Date, ModuleBuilder> moduleBuildersByRevision = modules
+            final TreeMap<Date, ModuleBuilder> moduleBuildersByRevision = modules
                     .get(dependentModuleName);
+            if (moduleBuildersByRevision == null) {
+                throw new YangParseException(
+                        "Failed to find dependent module '"
+                                + dependentModuleName + "' needed by module '"
+                                + module.getName() + "'.");
+            }
             if (dependentModuleRevision == null) {
                 dependentModule = moduleBuildersByRevision.lastEntry()
                         .getValue();
@@ -710,36 +1064,10 @@ public class YangModelParserImpl implements YangModelParser {
         return dependentModule;
     }
 
-    /**
-     * Get module import referenced by given prefix.
-     *
-     * @param builder
-     *            module to search
-     * @param prefix
-     *            prefix associated with import
-     * @return ModuleImport based on given prefix
-     */
-    private ModuleImport getModuleImport(ModuleBuilder builder, String prefix) {
-        ModuleImport moduleImport = null;
-        for (ModuleImport mi : builder.getModuleImports()) {
-            if (mi.getPrefix().equals(prefix)) {
-                moduleImport = mi;
-                break;
-            }
-        }
-        return moduleImport;
-    }
-
-    private Date createEpochTime() {
-        Calendar calendar = Calendar.getInstance();
-        calendar.setTimeInMillis(0);
-        return calendar.getTime();
-    }
-
     private static class SchemaContextImpl implements SchemaContext {
         private final Set<Module> modules;
 
-        private SchemaContextImpl(Set<Module> modules) {
+        private SchemaContextImpl(final Set<Module> modules) {
             this.modules = modules;
         }
 
@@ -783,6 +1111,31 @@ public class YangModelParserImpl implements YangModelParser {
             }
             return extensions;
         }
+
+        @Override
+        public Module findModuleByName(final String name, final Date revision) {
+            if ((name != null) && (revision != null)) {
+                for (final Module module : modules) {
+                    if (module.getName().equals(name)
+                            && module.getRevision().equals(revision)) {
+                        return module;
+                    }
+                }
+            }
+            return null;
+        }
+
+        @Override
+        public Module findModuleByNamespace(final URI namespace) {
+            if (namespace != null) {
+                for (final Module module : modules) {
+                    if (module.getNamespace().equals(namespace)) {
+                        return module;
+                    }
+                }
+            }
+            return null;
+        }
     }
 
 }